A year and a half ago, my partner and I went to a workshop on vermicomposting. We came home with a bin, worms, and heads full of knowledge. We were prepared. We were excited. We were in for months of fruit fly invasions, swampy smells seeping up from our basement, and various other surprises. Like slugs. And slimy mould.
But we survived and so did the worms. Those little critter are so prolific that last month I gave away 7 litres of them to good homes. I also gave lots of advice. Here are the basics for starting your own worm compost bin.
Reasons to Vermicompost
- It can be done anywhere as the worms don't take up much space.
- Valuable resources are kept out of the landfill and it helps reduce greenhouse gases.
- Your garden will love you!
- Worms are quiet, low maintenance and actually quite interesting.
- Worms work fast, so you'll have compost in no time.
Feeding Your WormsRed Wrigglers will eat most kitchen waste. Any fruit or vegetable waste that you generate during food preparation can be used, such a s carrots, lettuce, cabbage, celery, apples, banana peels, and tea leaves and bags. Citrus peels, coffee grounds and tomatoes can be added, but only in moderation, as they will acidify the bedding. Adding dried crushed eggshells will help to control acidity, and will also provide the worms with valuable nutrition. The worms are even interested in very small amounts of such leftovers as spaghetti, grain cereal, bread and pancakes.
NOTE: Avoid feeding your worms meat, fish, bones, dairy products and oily foods. These foods will cause odours and attract unwanted insects. Garlic, salt, vinegar and spicy leftovers should not be added, nor should large quantities of onions. These foods can hurt the worms.
Climate and TemperatureRed Wrigglers prefer temperatures between 15 – 25°C. Lower than 10°C or higher than 30°C can result in death. I've been told that red wrigglers can be added to your outdoor compost bin, but I haven't tried this yet. They will apparently move to the areas of the bin that aren't too hot, though in some climates, I think the temperature would be too much for them. They will not survive the winter in cold climates, but their eggs should, and they will hatch baby worms the next spring.
BeddingIt is necessary to provide a bedding for the worms to live in, and to bury food waste in. Suitable bedding materials are shredded newspaper and cardboard, shredded fall leaves, chopped up straw and other dead plants, seaweed, sawdust, compost and aged manure. I usually use either shredded newspaper or chopped up cardboard egg cartons, since we have both around the house. I don't use glossy magazine or flyer paper, though I'm not sure if that is really a no-no, or if it just seems more toxic to me.
HarvestingDivide and Harvest: Shift all the old bedding, castings and worms in the bin to one side. Add fresh bedding to the other side. Bury fresh scraps in the new bedding for a few weeks, and keep the new bedding covered. Leave the old bedding uncovered. Check after a week or two; the worms will have migrated to the fresh bedding. Harvest the compost then fill the empty side with fresh bedding. This only works well if you do it regularly. If you get too much compost in the bin, the next method works better.
Dump and Hand Sort: Place a large sheet of plastic on the floor or on a table. Dump the entire contents of the bin onto the sheet. Shape the compost into cone-shaped mounds. Shine a bright light above the mounds; this will drive the worms toward the bottom interior of each mound. Wait 5-10 minutes then gently scrape off the layers of compost until all you have left is worms. (You may see tiny, lemon-shaped cocoons; these contain baby worms, so be sure to add them to the new bin.)
Smells: When the lid is on, a well-maintained bin is odorless; when opened, it should have little smell - if any, the smell is earthy. Worms require gaseous oxygen. Oxygen can be provided by airholes in the bin, occasional stirring of bin contents, and removal of some bin contents if they become too deep or too wet. If decomposition becomes anaerobic from excess feedstock added to the bin in wet conditions; or layers of food waste have become too deep, the bin will begin to smell like ammonia.
Moisture: If bin is too wet, the smelly, excess waste water must be removed and the bin returned to a normal moisture level. To do this, first reduce addition of food scraps with a high moisture content and second, add fresh, dry bedding such as shredded newspaper to your bin, mixing it in well. If the bin is too dry (not a common problem), then lightly moisten the bedding before adding it. To control both moisture levels and fruit flies, I freeze everything first, then thaw it, drain off the moisture, and then add it to the bin. We also have our bin set up on and angle, and drain the compost tea from the one corner using a turkey baster. If you are just setting up a bin, then get two containers. Drill holes in the bottom of one, and then set it into the other. Make sure it is a tight fit, or you will have fruit flies.
Pests: Fruit flies breed in the bins if fruit and vegetable waste is not thoroughly covered with bedding. This problem can be avoided by thoroughly covering the waste by at least 2 inches of bedding. Maintaining the correct pH (close to netural) and water content of the bin (just enough water so that the compost is like a squeezed out sponge) can help avoid these pests as well. Slugs can also be a problem if outdoor leaves or grass clippings are added to the bin. Slugs found in the bin can be picked out and disposed of. Do this regularly until no slugs appear. To avoid slugs, do not use outdoor materials.
Worms escaping: Worms generally stay in the bin, but may try to leave the bin when first introduced, or often after a rainstorm when outside humidity is high. Maintaining adequate conditions in the worm bin and putting a light over the bin when first introducing worms should eliminate this problem.
Preventing die-off: Worms will regulate their own population according to the conditions of their environment. These conditions include space, moisture, pH, temperature, bedding material, and amount of food, among others. A typical household worm bin might start out with one pound of worms (approximately 1,000 adults), which will soon multiply to 2,000–3,000 if conditions are good. Conversely, if one or more of the above conditions are unacceptable, the worms may “crawl” (leave the bin) or die off. Maintaining adequate moisture and harvesting the compost before the bin gets too full are the most important things to do to prevent die-off.